#![allow(unused_imports)]
#![allow(non_snake_case)]
use std::collections::HashMap;
use std::collections::HashSet;

#[allow(unused_macros)]
macro_rules! read {
    ([$t:ty] ; $n:expr) =>
        ((0..$n).map(|_| read!([$t])).collect::<Vec<_>>());
    ($($t:ty),+ ; $n:expr) =>
        ((0..$n).map(|_| read!($($t),+)).collect::<Vec<_>>());
    ([$t:ty]) =>
        (rl().split_whitespace().map(|w| w.parse().unwrap()).collect::<Vec<$t>>());
    ($t:ty) =>
        (rl().parse::<$t>().unwrap());
    ($($t:ty),*) => {{
        let buf = rl();
        let mut w = buf.split_whitespace();
        ($(w.next().unwrap().parse::<$t>().unwrap()),*)
    }};
}

#[allow(dead_code)]
fn rl() -> String {
    let mut buf = String::new();
    std::io::stdin().read_line(&mut buf).unwrap();
    buf.trim_end().to_owned()
}


fn main() {
    let dist = read!(i32, i32);
    let obst = read!(i32, i32);
    let ops = [(-1i32, -1i32), (-1, 0), (-1, 1), (0, 1), (0, -1), (1, -1), (1, 0), (1, 1)];

    let mut open = vec![((0i32, 0i32), 0, obst.0.max(obst.1))];

    let mut close = HashSet::new();
    close.insert((0i32, 0i32));

    while let Some((coord, g, _)) = open.pop() {
        if coord.0 == dist.0 && coord.1 == dist.1 {
            println!("{}", g);
            return;
        }
        for op in ops.iter() {
            let new_coord = (op.0 + coord.0, op.1 + coord.1);
            if new_coord.0 == obst.0 && new_coord.1 == obst.1 {
                continue;
            }
            if close.insert(new_coord) {
                open.push((new_coord, g + 1, (new_coord.0 - dist.0).abs().max((new_coord.1-dist.1).abs())));
            }
        }
        open.sort_by_key(|(_, g, h)| std::cmp::Reverse(g+h));
    }
}